J. Nannoplankton Res. 32 (2), 2012, pp53-57 © 2012 International Nannoplankton Association
ISSN 1210-8049 Printed by Harcourt Colour Print, Swansea

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Two new Cretaceous calcareous nannofossils fromSE Spain and Tunisia
Roque Aguado

Dpto. Geología, Escuela Politécnica Superior de Linares, Universidad de Jaén, Alfonso X El Sabio 28, E23700 Linares, Spain;
raguado@ujaen.es
Manuscript Received 04th November, 2011; Manuscript Accepted 19th April, 2012.

Abstract Recent calcareous nannofossil research of three late Hauterivian to earliest Barremian sections from SE

Spain and two latest Cenomanian to earliest Turonian sections (S Spain and Tunisia) has revealed two new calcareous
nannofossil taxa Discorhabdus hannibalis and Micrantholithus spinulentus. D. hannibalis was found throughout thelatest Cenomanian to earliest Turonian, whilst M. spinulentus was observed from the late Hauterivian to the earliest
Barremian. Both species are described and illustrated here.

Keywords Calcareous nannofossils, taxonomy, Hauterivian–Barremian, Cenomanian–Turonian, SE Spain,
Tunisia.

1. Introduction
Subbetic (SE Spain) late Hauterivian to early Barremian
sediments have been investigated for ammonite and calcareous nannofossil content. Special attention has been
paid to the direct correlation between nannofossil andammonite biostratigraphy (Aguado et al., 2001, 2008;
Company et al., 2003, 2005a), the biotic and isotopic
characterization of the latest Hauterivian Faraoni Levelequivalent (FLE) (Aguado et al., 2003, 2008; Company etal., 2005a, 2007) and the proposal of a section in the Río
Argos area (X.Ag1 section, Figure 1A) as a global boundary stratotype section and point (GSSP) for the base of
the Barremian (Company et al., 2005b, 2011). We havealso investigated the Cenomanian/Turonian boundary

sediments in the Penibetic (El Chorro section, SE Spain;
Sánchez-Quiñonez et al., 2010) and Oued Bahloul (central Tunisia) for planktonic foraminifer and nannofossil
content in order to gain a better knowledge about the biostratigraphy and paleoceanography of this interval.
These works have uncovered a new pentalith nannofossil, assigned to the genus Micrantholithus, and a newplacolith, assigned here to the genus Discorhabdus. The
aim of this short note is to formally describe and illustratethese two new nannofossil species.
2. Material
Detailed bed-by-bed sampling was performed throughout the upper Hauterivian to lower Barremian sediments

Figure 1: General location of the study sections. A, Río Argos (X.Ag1 and X.Ag5) and Arroyo de Gilico (X.V1) sections. B, El Chorro (CHO)
section. C, Oued Bahloul (OB10) section. X.EC = Ermita de Cuadros section. X.G1 = La Guardia section.

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Aguadoof the Subbetic (SE Spain). In two sections from the Río
Argos area (X.Ag1: 38º 4’ 13” N, 1º 56’ 55” W; X.Ag.5:
38º 4’ 19” N, 1º 56’ 31” W; 2.7 km NNE of the village ofBarranda, Figure 1A) and in the Arroyo de Gilico section(X.V1: 38º 9’ 36” N, 1º 40’ 42.5” W; 12.7 km NE of the village of Cehegín, Figure 1A), more than 116 samples werecollected from marly lithologies and examined for nannofossil content. The sampled interval corresponds to part of
the Carretero Formation and is equivalent to nannofossil
Subzones NC5B and NC5C (X.Ag1 and X.Ag5 sections),
and NC5B to lowest part of NC5D (X.V1 section) using
the zonation of Bralower et al. (1995). The three sections
studied encompass the Hauterivian/Barremian boundary
and, in addition, the Río Argos sections contain a discreteinterval of latest Hauterivian age black shales, identified
as the FLE (Aguado et al., 2003, 2008; Company et al.,2005a, 2007). For details about the lithostratigraphy andthe ammonite and nannofossil biostratigraphy of these
sections, see Aguado et al. (2001, 2003, 2008) and Company et al. (2003, 2005a, 2005b, 2011).
The Oued Bahloul (OB10) section (35º 46’ 18” N, 9º
21’ 4” E ) is located in central Tunisia, about 5 km SSWof the village of Kasra (Figure 1C), and contains sediments of latest Cenomanian – earliest Turonian age (seeMaamouri et al., 1994; Amédro et al., 2005; Robaszynski et al., 2010 for descriptions of lithology, ammonite
and carbon-isotope stratigraphy). A total of 25 samples
were collected, covering the uppermost part of the Fahdène Formation, the complete Bahloul Formation, andthe lowest part of the Aleg Formation, and subsequently
examined for calcareous nannofossil and planktonic foraminiferal content. Moderately to well-preserved calcareous nannofossil assemblages allowed the identification of
the UC3c–UC3d, UC3e, UC4, UC5a, UC5c, UC6a, andUC6b Zones/Subzones of Burnett (1998).
The El Chorro (CHO) section (36°54'54" N, 4°46'16"W) is located in southern Spain, about 8.4 km WSW of
the village of Valle de Abdalajís (Figure 1B). A complete
lithological description, and details of fossil content, canbe found in Martín-Algarra (1987) and Rodríguez-Tovar
et al. (2009). Calcareous nannofossils were investigatedin 38 samples taken from the Capas Blancas Formation
throughout the latest Cenomanian to earliest Turonian
interval. Calcareous nannofossil assemblages are moderately to poorly preserved and allowed identification of theZones/Subzones UC3a–UC3d, UC6 and UC7. Full calcareous nannofossil biostratigraphical and palaeoecological data on the OB10 and CHO sections will be provided
in separate publications.
3. Methods
For the samples from the Río Argos and Arroyo de Gilico
sections, simple smear slides (Bown and Young, 1998)
were mounted with coverslips using Canada balsam,
while for the samples from the Oued Bahloul section,
the smear slides were prepared following the decantation
method described in Geisen et al. (1999) for quantitative analysis of the nannofossil assemblages. In addition,
temporary mobile mounts, to allow rotation of nannofos-

sil specimens, were also made using immersion oil, andfinally some samples were selected for analysis under thescanning electron microscope (SEM).
Smear slides were examined for nannofossil content
using a polarizing light microscope Olympus BHSP at
1200x magnification, and SEM samples were examinedwith a FESEM Carl Zeiss SMT Auriga at the Centro deInstrumentación Científica, University of Granada. Digital images were captured with an Olympus Camedia
C5050 camera at 1024x768 pixels (light micrographs)
and with a CrossBeam FIB workstation at 3072x2304
pixels (SEM micrographs). The plate images were taken
under cross-polarized light (XPL), inserting gypsum plate(GP), or using SEM (SEM). In the GP images, the fast rayin the gypsum plate was orientated NW–SE.
4. Systematic palaeontology
The taxonomic descriptions below follow the terminology guidelines of Young et al. (1997). Only taxonomic
references that do not appear in Bown (1998) are provided
in the reference list. In the following descriptions, D =diameter, H = height. The reference biozonations are from
Bralower et al. (1995) for the Hauterivian – Barremianand Burnett (1998) for the Cenomanian – Turonian.
4.1. Heterococcoliths
Order PODORHABDALES Rood, 1971,
emend. Bown, 1987
Family BISCUTACEAE Black, 1971
Discorhabdus hannibalis sp. nov.
Pl. 1, Figures 1–20, 25
Derivation of name: As this species was originally observed in samples from Tunisia (ancient Carthage), it isnamed after Hannibal, the famous Carthaginian general,
who married the Iberian princess Himilce in the ancient
city of Castulo (now Linares, SE Spain).
Diagnosis: Small to very small species of Discorhabdus with two closely appressed shields. Unlike other species in this genus, the proximal shield of D. hannibalis
is wider than the distal shield, protruding beyond it (Pl.
1, Figures 1, 10–13). Typically, the proximal shield is atleast twice as thick as the distal shield in side view (Pl.1,
Figures 10–13). It usually comprises 10 wedge-shaped,
radially-arranged and subtly dextrally-imbricated elements, showing high birefringence and radial c-axis (Rcrystal units), when observed under cross-polarized lightin plan view. The smaller distal shield consists of an equal
number of elements with faint birefringence (vertical caxis, V-crystal units) under cross-polarized light, and isusually not visible when observed in plan view.
Differentiation: In plan view and cross-polarized
light, this species can be differentiated from top views of
Nannoconus and plan views of Eprolithus using the gypsum plate. D. hannibalis shows radial orientation of thec-axis (Pl. 1, Figures 3, 5, 7, 9, 15, 17), whereas Nannoconus and Eprolithus display tangential orientation of thec-axis. In plan view, this species is distinct from other species of Discorhabdus (e.g., D. ignotus: Pl. 1, Figures 23,

Two new Cretaceous calcareous nannofossils from SE Spain and Tunisia

Plate 1
SEM and light micrographs of D. hannibalis and M. spinulentus. (SEM) = SEM image; (XPL) cross-polarized light;(GP) gypsum plate inserted. Each GP micrograph corresponds to the same specimen in the XPL micrograph placed
to its left side.

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Aguado25) in having higher birefringence under cross-polarized
light (Pl. 1, Figures 2, 4, 6, 8, 14, 16, 18–20, 25). Unlike
other species in this genus (e.g., D. ignotus, Pl. 1, Figure24), the side views of D. hannibalis (Pl. 1, Figures 10–13)
are characterized by having a proximal shield wider andthicker than the distal shield.
Remarks: Although this species has a typical placolith
structure, it has a peculiar shield construction (proximal
shield wider and thicker than the distal one) that is notseen in any other species of the genus Discorhabdus.
Holotype: Pl. 1, Figures 6, 7 (are the same specimen).
Holotype dimensions: D = 3.7 μm.
Paratypes: Pl. 1, Figures 1 (D = 3.16 μm). Pl. 1, Figures 10, 11 (are the same specimen, D = 4 μm, H = 2 μm).
Pl 1, Figures 14, 15 (are the same specimen, D = 4.4 μm).
Type locality: Oued Bahloul section, about 5 km SSWof the village of Kasra, central Tunisia (35º 46’ 18” N, 9º
21’ 4” E).
Type level: Sample OB-3.5, upper Fahdène Formation, upper Cenomanian (Subzone UC3c–UC3d).
Occurrence: Oued Bahloul (Tunisia), upper Cenomanian to lower Turonian (Subzone UC3c–UC6c); El Chorro section (Betic Cordillera, Spain), lower Cenomanian(Zone UC3).
4.2. Nannoliths
Family BRAARUDOSPHAERACEAE Deflandre, 1947
Micrantholithus spinulentus sp. nov.
Pl.1, Figures 21, 22, 26, 27
1988 Micrantholithus sp. Applegate and Bergen, pl. 29,
figure 13.
1993 Micrantholithus sp. 1 Aguado, pl. 21, figures 13, 14.
2005 Micrantholithus sp. 1 Company et al., figures 7.37–
7.39.
Derivation of name: From the Latin, ‘spinulentus’,
meaning ‘spinous, prickly’, alluding to its outline.
Diagnosis: A Micrantholithus species characterized
by its very large size (14–25 µm) and deeply indented
sides, which usually results in medium to long free rays.
Typically, the free-ray length is nearly equal to, or slightly
greater than, the radius of the central body in each pentalith.
Differentiation: This species can be differentiatedfrom other Lower Cretaceous species of the genus Micrantholithus by its greater size (typically >14 µm in diameter), deeply indented sides, and long rays. M. spinulentus broadly resembles some Paleogene forms, such as
M. attenuatus Bramlette and Sullivan, 1961, M. excelsus
Bown, 2005 and M. hebecuspis Bown, 2005. However,M. attenuatus and M. excelsus differ from M. spinulentus
in having more gracile, longer rays, and M. hebecuspis
has blunt, flat-ended apices. M. spinulentus appears to be
restricted to the upper Hauterivian and lower Barremianinterval (Company et al., 2005, 2011).
Remarks: The Micrantholithus segments illustrated
by Bown (2005), in pl. P11, figure 28, and found at Site
1214 from Leg 198 (Shatsky Rise, northwestern Pacific

Ocean), probably correspond to M. spinulentus.
Holotype: Pl. 1, Figure 21.
Holotype dimensions: D = 16.7 μm.
Paratypes: Pl. 1, Figure 22 (D = 15.6 μm) and Pl. 1.
Figure 26 (D = 20.7 μm).
Type locality: Arroyo de Gilico section (X.V1), about
12.7 km NE of the village of Cehegín, Murcia province,
SE Spain (38º 9’ 36” N, 1º 40’ 42.5” W).
Type level: Sample X.V1.-7, upper Hauterivian (NC5B
Subzone, C. krenkeli ammonite Subzone).
Occurrence: This species was found throughout theupper Hauterivian to lowermost Barremian sediments of
the Galicia Margin (Applegate & Bergen, 1988) and theSubbetic (Aguado, 1993; Company et al., 2005, 2011).
In the Subbetic, M. spinulentus was found in various sections of the Río Argos area (X.Ag1, X.Ag5) and in the
Arroyo de Gilico (X.V1) section (Company et al., 2005;2011) throughout Subzones NC5B and most of NC5C (C.
krenkeli to P. colombiana ammonite Subzones). It has
also been found in the upper Hauterivian to lowermost
Barremian in the Ermita de Cuadros (X.EC) and La Guardia (X.G1) sections (Figure 1), located in the Intermediate
Domain of the Subbetic (pers. observ.). Its last occurrence
is observed in the beds equivalent to the upper part of theearliest Barremian Subzone NC5C (upper part of the P.
colombiana ammonite Subzone).
5. Acknowledgements
The author is very grateful to A. Carrillo (Dpto. Geología,
Univ. Jaén) and to A. González (Centro de Instrumentación Científica, Univ. Granada) for their help in sample
processing and SEM examination. C. Laurin corrected
the English version of the text. I also acknowledge Dr.
Liam Gallagher and two anonymous referees for criticalreviews and constructive suggestions. This study constitutes part of the results of Research Projects CGL200502500, CGL2008-00533 and CGL2011-23759, supportedby the DGI (Dirección General de Investigación, Spain),and of the RNM-200 Research Group (Junta de Andalucía, Spain).
References
Aguado, R. 1993. Nannofósiles del Cretácico de la Cordillera Bética. Bioestratigrafía. PhD Thesis, Universidad de Granada, Granada: 413 pp.
Aguado, R., Company, M., Sandoval, J. & Tavera, J.M.
2001. Caracterización bioestratigráfica del límite
Hauteriviense–Barremiense en las Cordilleras Béticas.
Geotemas, 3: 127–130.
Aguado, R., Company, M., Sandoval, J. & Tavera, J.M.
2003. Cambios bióticos en relación con un evento
anóxico menor ("nivel Faraoni", Hauteriviense terminal, Cretácico inferior). In: M. A. Lamolda (Ed.),
Bioevents: their stratigraphical records, patterns andcauses. Ayuntamiento de Caravaca de la Cruz: 76.
Aguado, R., Company, M., O'dogherty, L., Palomo, I.,
Sandoval, J. & Tavera, J.M. 2008. Integrated stratigraphy of the uppermost Hauterivian–Lower Barremianpelagic sequence of Arroyo Gilico (Betic Cordillera,

Two new Cretaceous calcareous nannofossils from SE Spain and Tunisia

SE Spain), First International Meeting on Correlations of Cretaceous Micro- and Macrofossils. Berichte
der Geologischen Bundesanstalt in Wien: 36–37.
Amédro, F., Accarie, H. & Robaszynski, F. 2005. Position de la limite Cénomanien–Turonien dans la Formation Bahloul de Tunisie centrale: apports intégrés desammonites et des isotopes du carbone (δ13C) Eclogae
Geologicae Helvetiae, 98: 151-167.
Applegate, J.L. & Bergen, J.A. 1988. Cretaceous calcareous nannofossil biostratigraphy of sediments recovered from the Galicia Margin, ODP Leg 103. In: G.
Boillot, E.L. Winterer, et al. (Eds.), Proceedings of the
Ocean Drilling Program Scientific Results: 293–348.
Bown, P.R. 1998. Calcareous nannofossil biostratigraphy. British Micropalaeontological Society Publication Series. Chapman & Hall, London: 314 pp.
Bown, P.R. 2005. Early to mid-Cretaceous calcareous
nannoplankton from the Northwest Pacific Ocean, Leg
198, Shatsky Rise. In: T.J. Bralower, I. Premoli-Silva,& M.J. Malone (Eds.), Proceedings of the Ocean
Drilling Program Scientific Results: 1–82.
Bown, P.R. & Young, J.R. 1998. Techniques. In: P.R.
Bown (Editor), Calcareous nannofossil biostratigraphy. British Micropalaeontological Society Publication Series. Chapman & Hall, London: 16¬–28.
Bralower, T.J., Leckie, R.M., Sliter, W.V. & Thierstein,
H.R. 1995. An integrated Cretaceous microfossil biostratigraphy. In: W.A. Berggren, D.V. Kent et al. (Eds.),
Geochronology, Time Scales and Global Stratigraphic
Correlation. The Society of Economic Paleontologists
and Mineralogists Special Publication 54: 65–79.
Burnett, J.A. 1998. Upper Cretaceous. In: P.R. Bown
(Ed.), Calcareous nannofossil biostratigraphy. British Micropalaeontological Society Publication Series.
Chapman & Hall, London: 132–199.
Company, M., Aguado, R., Baudin, F., Coccioni, R.,
Deconinck, J.F., Frontalini, F., Giusberti, L., Martínez, M., Moiroud, M., O’Dogherty, L., Pellenard,
P., Rawson, P.F., Riquier, L., Romero, G., Sandoval,J., Tavera, J.M. & Weissert, H. 2011. La sección de
Río Argos (Caravaca, Murcia), candidata a GSSP dellímite Hauteriviense–Barremiense (Cretácico inferior). XXVII Jornadas Sociedad Española de Paleontología. Paleontología i evolució, Memòria Especial
5: 75–78.
Company, M., Aguado, R., Jiménez de Cisneros, C.,
Sandoval, J., Tavera, J.M. & Vera, J.A. 2003. Bioticchanges at the Hauterivian/Barremian boundary in
the Mediterranean Tethys. In: M. A. Lamolda (Ed.),
Bioevents: their stratigraphical records, patterns andcauses. Field-trip guide. Ayuntamiento de Caravaca dela Cruz: 15–28.
Company, M., Aguado, R., Sandoval, J. & Tavera, J.M.
2007. El evento anóxico Faraoni (Hauteriviense
superior) en el Río Argos (Caravaca, SE de España):
posibles causas y efectos. In: J. Aguirre, M. Company& F.J. Rodríguez-Tovar (Eds.), XXIII Jornadas de laSociedad Española de Paleontología (caravaca de la
Cruz, 3-6 de Octubre de 2007). Guía de excursiones.

57

Instituto Geológico y Minero de España y Universidad
de Granada: 19–32.
Company, M., Aguado, R., Sandoval, J., Tavera, J.M.,
Jiménez de Cisneros, C. & Vera, J.A. 2005a. Bioticchanges linked to a minor anoxic event (Faraoni level,
latest Hauterivian, Early Cretaceous). Palaeogeography, Palaeoclimatology, Palaeoecology 224: 186–199.
Company, M., Sandoval, J., Tavera, J.M., Aguado, R. &O'dogherty, L. 2005b. La sección de Río Argos (Caravaca, Murcia), referente global para el estudio dellímite Hauteriviense-Barremiense (Cretácico Inferior).
In: M. A. Lamolda (Ed.), Geociencias, recursos y patrimonio geológicos. 30º Aniversario del Comité Nacional Español, PICG 1975-2005. Instituto Geológico y
Minero de España: 129–134.
Geisen, M., Bollmann, J., Herrle, J.O., Mutterlose, J. &Young, J.R. 1999. Calibration of the random settlingtechnique for calculation of absolute abundances ofcalcareous nannoplankton. Micropaleontology, 45:
437–442.
Maamouri, A.L., Zaghbib-Turki, D., Matmati, M.F.,
Chikhaoi, M. & Salaj, J. 1994. La Formation Bahloul
en Tunisie centro-septentrionale: variations latérales,
nouvelle datation et nouvelle interprétation en terme
de stratigraphie séquentielle. Journal of African Earth
Sciences, 18, 37–50.
Martín-Algarra, A. 1987. Evolución geológica alpina delcontacto entre las Zonas Internas y las Zonas Externasde la Cordillera Bética. PhD Thesis, Universidad deGranada, Granada: 1171 pp.
Robaszynski, F., Zagrarni, M.F., Caron, M. & Amédro,F. 2010. The global bio-events at the Cenomanian–Turonian transition in the reduced Bahloul Formation of Bou Ghanem (central Tunisia). Cretaceous
Research, 31: 1–15.
Rodríguez-Tovar, F.J., Uchman, A., Martín-Algarra, A. &O'dogherty, L. 2009. Nutrient spatial variation during
intrabasinal upwelling at the Cenomanian–Turonian
oceanic anoxic event in the westernmost Tethys: An
ichnological and facies approach. Sedimentary Geology, 215: 83–93.
Sánchez-Quiñonez, J.A., Alegret, L., Aguado, R., Delgado, A., Cruz Larrasoaña, J., Martín-Algarra, A.,
O'dogherty, L. & Molina, E. 2010. Foraminíferos deltránsito Cenomaniense–Turoniense en la sección de El
Chorro, Cordillera Bética, sur de España. Geogaceta,
49: 23–26.
Young, J.R., Bergen, J.A., Bown, P.R., Burnett, J.A.,
Fiorentino, A., Jordan, R.W., Kleijne, A., Van Niel,
B., Romein, A.J.T. & Von Salis, K. 1997. Guidelines
for coccolith and calcareous nannofossil terminology.
Palaeontology, 40: 875–912.